1961—2016年我国闪电日数时空分异格局及其变化趋势和波动特征

闪电事件时空变化研究对于防灾减灾和资源利用具有重要意义。采用2 481个站点的闪电日数数据诊断1961—2016年我国闪电事件的时空演变特征。结果表明：在时间上，1961—2016年我国年均单站闪电日数整体呈减少趋势，西北西部和西藏地区年均单站闪电日数呈分段变化特征。全国、东北、北方、西北东部和东南地区年均单站闪电日数大致呈2~4 a的周期变化。西北西部、西藏和西南地区分别呈2，4和6 a，3和8 a与2~6 a的显著周期变化。年均单站闪电日数突变集中发生在20世纪80年代末至90年代中后期，但均未通过0.05显著性水平检验。在空间上，1961—2016年我国年均闪电日数呈明显的“南多北少”的空间分布格局。1961—1980年，胡焕庸线以东地区闪电日数主要以正距平为主，1980年以后，正距平范围逐渐减少。在变化趋势的空间分布上，我国闪电日数年际变化趋势整体上以减少为主，尤其是长江以南的沿海地区减少明显；在波动特征的空间分布上，青藏高原、华北平原、沿长江两岸附近地区均为闪电日数年际波动较大的地区，而长江以南的沿海地区和新疆中部及北部地区年际波动相对较小。

Temporal and spatial patterns of lightning days and its tendency and fluctuation from 1961 to 2016

The temporal and spatial distribution characteristics of lightning events in China from 1961 to 2016 are calculated by using the yearly dataset of 2 481 stations’ lightning days. The results show that: On the dimension of time, the average annual lightning days in China and the seven geographical regions show a decreasing trend from 1961 to 2016. At the same time, the annual average number of single station lightning days in northwest China and Tibet region shows the characteristics of piecewise variation. The annual average single station lightning days in the whole country, northeast china, north China, eastern Northwest China and southeast China have oscillation periods about 2 to 4 a. There are significant oscillation periods of 2, 4 and 6 a, 3 and 8 a, and 2 to 6 a in the western northwest China, Tibet and southwest China， respectively. The annual single station lightning day mutation occurs in the whole country and seven geographical regions from 1980s to the middle and late 1990s, but none of them passes the test of P<0.05 significant level. On the dimension of space, Chinese annual lightning days show a clear "south high- north low" spatial distribution pattern from 1961 to 2016. The lightning days in the east of the Huhuanyong line are dominated by the positive anomaly from 1961 to 1980, and the range of the positive anomaly decreases successively after 1980. For the trend of spatial distribution, the annual trend of lightning days in China is mainly on the decrease, especially in the coastal areas of south of the Yangtze River. For the spatial distribution of fluctuation characteristics, the Qinghai Tibet Plateau, the North China Plain and the vicinity of both sides of the Yangtze River are the regions whose annual fluctuation of lightning days is large. The annual fluctuations of the coastal areas of south of the Yangtze River and the central and northern parts of Xinjiang are relatively small.